This invention concerns beverage dispensers and a method for using beverage dispensers. In particular, the field of the invention relates to an automatic shut off valve for a dispenser and a method of using the dispenser to minimize energy usage and heating of the dispensed beverage.
Fast service restaurants need equipment that makes their employees as efficient as possible. Every task in food preparation and service has long been analyzed, and restaurant kitchens and food preparation areas are now designed and laid out with efficiency and total-cost-of-ownership in mind. One very important area in food service is the beverage dispensing function. It is an area that is relatively well disposed to mechanization and automation, since there are standard sizes (small, medium, large, and some variation of super-size or extra large) for most beverages. There is certainly a need to minimize the time an employee spends waiting for a soft-drink dispenser to fill up a cup. Therefore, some soft-drink dispensers now have solenoid-operated valves that can automatically shut off. Other restaurants have resorted to self-service, with the customers themselves dispensing the drinks, freeing employees from this task, but losing control over the machine in the process.
Prior art patents, such as U.S. Pat. Nos. 4,712,591 and 4,753,277, disclose beverage dispensing machines with automatic shut-offs that utilize an electrical circuit that passes through the beverage. That is, one electrode from a controller is placed in the soft-drink stream, usually at or near the nozzle. When foam or beverage overflows the cup, the beverage makes contact with another electrode, completing an electrical path through the beverage and to the machine. This other electrode typically forms part of the lever a user presses to dispense a drink. A microprocessor detects the completed circuit and shuts the solenoid controlling the valve. These beverage dispensers suffer from a number of defects. One principal defect is that the current passes through the drink itself, flowing from the nozzle, through the drink to another electrode. Another disadvantage is that present valves and beverage dispensers must be designed and built to accommodate an electrical conductor in the nozzle that extends down to a container that will be filled with the beverage.
Other dispensers, such as those described in U.S. Pat. No. 3,916,963, depend on immersing an electrode or electrodes in the cup or container into which the beverage is dispensed. One defect of this design is that electrodes have to be placed in the cup. This can lead to unsanitary conditions, and could also undesirably mix an unwanted flavor into the drink being dispensed. These electrodes also add another component to the beverage mixing and dispensing valve. What is needed is a soft-drink dispenser having an automatic shut-off that does not have an electrical circuit that passes through the beverage or electrical conductors in the nozzle.
In order to address these deficiencies of the prior art, an automatic valve for a beverage dispenser has been invented. One aspect of the invention is an automatic shut-off valve for dispensing a beverage into a container. The automatic shut-off valve comprises at least one electrically-operated valve, a detection circuit comprising at least two spaced conductors, the detection circuit wholly external to the container and capable of detecting conductivity between the at least two spaced conductors, and a controller that shuts off the at least one electrically-operated valve automatically when liquid or foam from a beverage creates a conductive path between the at least two spaced conductors.
Another aspect of the present invention is a method of dispensing a beverage with an automatic shut-off valve. The method comprises providing a container having an open mouth, opening at least one electrically-operated valve to begin dispensing the beverage into the container, and detecting a change in an electrical detection circuit wholly external to the container while dispensing the beverage. The method also comprises automatically closing the electrically-operated valve upon detecting a change in the electrical detection circuit.
Another aspect of the invention is a method of dispensing a beverage into a container. The method comprises providing a container, opening at least one solenoid valve to fill the container with the beverage, and keeping the valve open by a pulse-width-modulation technique while operating a detection circuit wholly external to the container. The method also comprises closing the valve automatically upon detecting a change in the detection circuit.
Another aspect of the invention is a beverage dispenser for dispensing a beverage into a container. The beverage dispenser comprises at least one mixing and dispensing valve for dispensing a beverage, the at least one mixing and dispensing valve comprising at least one solenoid-operated valve for controlling a flow of at least one fluid, a detection circuit comprising at least two spaced conductors, the detection circuit wholly external to the container and capable of detecting conductivity between the at least two spaced conductors, and a controller that shuts off the at least one solenoid-operated valve automatically when beverage foam or liquid creates a conductive path between the at least two spaced conductors. The beverage dispenser also comprises a drip tray below the at least one mixing and dispensing valve and a housing for mounting the drip tray and the at least one mixing and dispensing valve.
The advantages of the beverage dispenser and the automatic shut-off valve used with the beverage dispenser include a simpler nozzle design that does not require an electrical conductor in the nozzle as a part of the detection circuit. The shut-off valve in the embodiments of the present invention has no detection electrode in the nozzle and does not make contact with the beverage in the container. The electrode thus does not mix undesired previous flavors into beverages which are dispensed afterwards. These and other aspects and advantages of the invention will be made clearer in the accompanying drawings and explanations of the preferred embodiments.